State Key Laboratory of Crop Genetics and Germplasm Enhancement, Agriculture Ministry Key Laboratory of Biology, Genetics and Breeding of Japonica Rice in Mid-lower Yangtse River, Nanjing Agricultural University, Nanjing, China.
Theor Appl Genet. 2013 Sep;126(9):2313-22. doi: 10.1007/s00122-013-2137-2. Epub 2013 Jun 8.
Low-temperature germination (LTG) is an important agronomic trait for direct seeding of rice in temperate regions of East Asia. To dissect the genetic control of LTG, we constructed a recombinant inbred line (RIL) population derived from a cross of japonica variety USSR5 and indica variety N22. Three putative QTL involved in LTG were detected and named qLTG-7, qLTG-9 and qLTG-12. They explained 9.5, 12.12 and 7.08 % of the phenotypic variation, respectively, and the alleles from USSR5 enhanced LTG. A set of advanced backcross lines selected for the presence of qLTG-9 (with the biggest contribution of the three QTL), by both linked markers and phenotype, was used to validate qLTG-9 in different generations, years and locations. A near-isogenic line in USSR5 background with a qLTG-9 insertion from N22 had retarded germination under low-temperature conditions. Finally, qLTG-9 was fine mapped between markers L9-25D and ID-1, to a 72.3-kb region in chromosome 9, which in the Nipponbare genome contains five predicted genes. This result provides a springboard for map-based cloning of qLTG-9 and is helpful in understanding the mechanism of seed germination under low-temperature conditions.
低温发芽（LTG）是东亚温带地区水稻直接播种的一个重要农艺性状。为了剖析 LTG 的遗传控制，我们构建了一个重组自交系（RIL）群体，该群体源自粳稻品种 USSR5 和籼稻品种 N22 的杂交。检测到并命名了三个与 LTG 相关的假定 QTL，分别命名为 qLTG-7、qLTG-9 和 qLTG-12。它们分别解释了表型变异的 9.5%、12.12%和 7.08%，来自 USSR5 的等位基因增强了 LTG。一组通过连锁标记和表型选择携带 qLTG-9 的先进回交系（三个 QTL 中贡献最大的），用于在不同世代、年份和地点验证 qLTG-9。在 USSR5 背景下带有来自 N22 的 qLTG-9 插入的近等基因系在低温条件下发芽迟缓。最后，qLTG-9 在标记 L9-25D 和 ID-1 之间被精细定位到 9 号染色体的 72.3-kb 区域，在粳稻基因组中包含五个预测基因。这一结果为 qLTG-9 的图谱克隆提供了跳板，有助于理解低温条件下种子发芽的机制。
